What is the meaning of this?

Move the points around in the app below. As you do, make sure you DO NOT place points on top of each other. Move these points around until you notice a new message.
Without Googling, what does it mean for point B to be [b]BETWEEN [/b]A and C. Describe.
Take a screenshot of this and include it in one of your Class notebooks, in the page called "in between". Then, read the secret assignment below.
Get up silently and make a human model of "A point between two other points". The point in between must be the person with the birthday in between the other 2 birthdays.
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– raquelteachesgeometry, Tim Brzezinski

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